Method for the recovery of sprayed paint material



Patented May 9, 1944 METHOD FOR THE RECOVERY OF SPRAYED PAINT MATERIALHarry E. Hoffman, Mansfield, Ohio No Drawing. Application July 6, 1939,

Serial N0. 283,079

6 Claims. (Cl. 106-287) The present invention relates to a method forthe recovery of waste sprayed paint material and more particularly to anew and useful method for the recovery of excess sprayed enamel materialfrom surfaces other than those purposely coated.

It has been the practice heretofore to spray surfaces with paint orenamel by placing paper or other sheet material on the surfaces adjacentto that to be paint sprayed so as to permit application of the enamelor'paint' with sharp edges or lines at the limits of the area to becovered. The method of spraying objects or surfaces with enamel or paintby the use of screens or shields behind the object has also been used toa considerable extent.

Generally the paper employed in the paint spraying operation hasbeendiscarded. and the screens or shields are usually washed with asuitable solvent to remove the excess enamel or paint which is thenthrown to waste.

I have discovered that the waste enamel or excess deposited spray may berecovered in a manner which is rapid, efficient and economical and thatthe material obtained in the recovery process may be directly used inthe paint material without isolating the pigment or vehicle associatedwith the pigment in the original material sprayed. The product may bereadily used by applying the material to the surface to be painted bymeans of a brush, and if desired the material may be readily purified tosuch an extent that it may be employed again for spraying in the samemanner as the original material.

a The preferred method of carrying out my invention is as follows,although it will be understood that I do not desire to be limited to thespecific method as described in detail, except as defined in the claimsannexed hereto:

The excess or waste enamel which has been applied to paper or to a metalor other surface is first treated with water before the material has hadan opportunity to harden so as to remove substantially all of theenamel, including the pigment and the non-volatile vehicle associatedwith it. If the enamel is to be recovered from paper. for example, theentire paper mass with the paint material thereon may be soaked for asufllcient time in water to soften and dislodge the coating material.Then the mass may be strained so as to filter off the paint materialfrom the paper mass. If the enamel to be recovered has been depositedupon a metal surface, the surface may be washed with water which may besprayed or pumped onto the surface so as to remove the adhering paintmaterial which may be passed into a sump or container from which the'water may be withdrawn after the sludge or paint mass has been allowedto settle. It will be understood that if water is sprayed onto the metalsheet or surface, the relative amounts are so large that it becomesnecessary for purposes of economy to use the water over and over byrecirculating and reusing for the successive surfaces to be cleaned, asotherwise the cost of recovery of the excess or waste enamel becomesexcessive.

From whatever source the enamel or paint material is derived by means ofthe water treatment, the material is allowed to settle for a sufficienttime so that the enamel or paint material forms a pasty mass at thebottom of the container in which it is allowed to settle and the watergradually separates and comes to the upper surface, forming a layer atthe upper portion of the container. The supernatant layer may be drawnoff or decanted, tp be used over again, if desired. or the water may bediscarded, provided that the amount is not excessive.

The enamel or paint material is then placed in a tank or receptacle inwhich it may be heated. A tank provided with a water bath is preferablyemployed so that the temperature may be controlled, providing thedesired amount of heat. The water bath is preferably maintained at theboiling point of water, by which the enamel is rapidly softened to suchan extent that it may be poured from the tank into other containers.

The softened enamel or paint material is then mixed with a petroleumdistillate vaporising more readily than kerosene and less readilythan.hightest gasoline, such as Vamolene,'which is a mineral oildistillate having greater volatility than kerosene and evaporating lessreadily than hightest gasoline. It may be defined as a petroleumfraction substantially free from aromatic hydrocarbons and containingnot over 2 per cent of unsaturated hydrocarbons, the said fractionhaving an initial boiling point between 300 F. and 310 F., a dry pointbetween 400 F. and 415 F., a flash point between .105 F. and F., a firepoint between F. and F., and a gravity between 49 B. and 50 B. I havediscovered that this mineral oil fraction has a very high solvent powerfor the partially dried vehicle associated with the ordinary enamel asmanufactured at the present time and serves also as a vehicle in theapplication of the recovered material and volatilizes at a rate so asnot to produce pin holes or cavities in the surface after the paintmaterial is applied.

It will be understood that many of the cheaper paints employ volatilesolvents or thinners usually low-boilinghydrocarbons, in place ofturpentine, to serve as a thinner to assist in the application of thepaint by means of a brush. without causing too much "drag" on the brush,but such materials, and in fact substantially all thinners on the marketproduce a deleterious effect in the application of the paint or enamel,by the production of blow-holes.

The commercial Varnolene has, I have discovered, solvent properties andspreading properties when admixed with waste or deposited enamels whichis not possessed by gasoline, gasoline mixtures with other mineral oildistillates or other numerous solvents now on the market.

The proportions of the enamel or paint sludge to Varnolene which Ipreferably employ are in the ratio of 5 gals. of sludge to from 2 to 2/2 gals. of Varnlene" although the ratio may be varied outside of theselimits and results which are wholly satisfactory obtained.

The mixture of sludge and "Varnolene" is stirred until a homogeneousmixture is obtained, the time generally required being about one hour,with batches of about 5 to 40 gallons of the sludge treated.

After a homogeneous mass is obtained, the material is preferablyfiltered or screened to remove undispersed masses or foreign solidswhich would otherwise produce specks or defects in the painted surface.I

After the material is filtered it is ready for use, but it is to beunderstood that the composition may be varied to some extent, dependingupon the use to which the paint is to be put. If it is to be used foroutside work, a small proportion of linseed oil may be added, such asone quart to the gallon of the product, and a small proportion ofthinner, preferably turpentine, may be added. For inside work, theproduct may be thinned with a small proportion of Varnolene" although itwill be understood that when the material is to be made for thisspecific purpose, a proportionately larger proportion of Varnolene maybe used in the method as above described.

Havingthus described the invention, what is claimed as new is:

l. A method for the recovery of excess sprayed enamel paint materialwhich comprises subjecting the excess sprayed enamel paint material totreatment with water to form a sludge containing pigment and theassociated vehicle, heating the said sludge until it is softenedsufficiently to readily flow, mixing the heated sludge with Varnolene,stirring the said mixture sufilciently to form a relatively homogeneousmass containing only a small proportion of undesired, undi tributedsolid masses and separating the said un esired masses from theadmixture.

2. A method for the recovery of excess sprayed paint material whichcomprises subjecting the said paint material to treatment with water,thus forming a sludge, removing the said water from the sludge, heatingthe sludge to render it soft so as to readily flow, mixing the heatedsludge with a petroleum distillate vaporizing more readily than keroseneand less readily than high test gasoline and corresponding substantiallyto Varnolene, stirring the admixture to form a relatively homogeneousmass and filtering the mass to remove undesired solid particlestherefrom.

3. A method for the recovery of excess sprayed enamel paint materialobtained during the process of enamel spray painting, which comprisessubjecting the excess enamel material to treatment with water to form asludge, allowing the sludge to settle, removing the water from theenamel material, heating the sludge to substantially the temperature ofboiling water, pouring the heated sludge into Varnolene," mixing thesludge with the "Varnolene" to obtain a substantially homogeneousadmixture, and screening the admixture to remove lumps or otherundesiredsolid rrlaterial therefrom.

4. A method for the recovery of excess sprayed enamel material fromsurfaces other than those purposely coated which comprises subjectingthe excess enamel material to the treatment with water to remove thesame from surfaces on which the spray is not desired, allowing the waterenamel mixture to stand to permit the enamel sludge to settle, removingthe water therefrom by decantation, heating the sludge to a temperatureat which the sludge may readily flow, admixing the sludge in theproportion of five gallons of sludge with from two to two and one halfgallons of Varnolene," stirring the admixture to obtain a homogeneousmass and removing undesired solids therefrom by filtering through aseries of screens, resulting in a paint material which may be applied tosurfaces to be painted by means of brushing or p aying.

5. A method for the recovery of excess sprayed paint material whichcomprises subjecting they said paint material to treatment with water toform a sludge, removing water from the sludge, heating the sludge torender it soft so as to readily flow, mixing the heated sludge with apetroleum distillate vaporising more readily than kerosene and lessreadily than high test gasoline, agitatingthe admixture to form arelatively homogeneous composition and removing undesired solid materialtherefrom.

6. A method for the recovery of excess sprayed paint material whichcomprises subjecting the said paint material to treatment with water toform a sludge, heating the sludge to render it soft so as to readily flomixing the heated sludge with a petroleum distillate vaporizing morereadily than kerosene and less readily than high-test gasoline,agitating the admixture to form a relatively homogeneous composition andremoving undesired solid material therefrom.

HARRY E. HOFFMAN.

